Implementation Guidance page added to technical.buildingsmart.org

[ReD_CoDE]

Thanks @jwouellette

Regarding to IfcXML I asked a question here which I think can improve it

[SOLVED] Where do I find computer interpretable pset assignments?

@sergej Does IFC is just based on XSD or have applied other solutions like Schematron too? More info: http://www.topologi.com/public/Schtrn_XSD/Paper_onlyXSD.html

CC: @TLiebich